KR20200011887A - Process for oligomerization of butene with determination of the proportion of acidic catalysis - Google Patents

Abstract

The present invention provides a method for manufacturing a product mixture by oligomerzing n-butene using a nickel-containing aluminosilicate catalyst, which accompanies determining and monitoring a ratio of 4,4-dimethylhexene to 3,4-dimethylhexene of the product mixture. The present invention also relates to a method for determining a ratio of the amount of formed 4,4-dimethylhexene or the amount of formed 3-ethyl-2-methylpentene to the amount of formed 3,4-dimethylhexene. An object of the present invention to provide an oligomerization method which makes it possible to achieve higher selectivity and higher conversion for a higher linear product.

Description

Process for oligomerization of butene with determination of the rate of acid catalysis {PROCESS FOR OLIGOMERIZATION OF BUTENE WITH DETERMINATION OF THE PROPORTION OF ACIDIC CATALYSIS}

The present invention provides a product mixture by oligomerizing n-butene using a nickel-containing aluminosilicate catalyst, which involves determining and monitoring the ratio of 4,4-dimethylhexene to 3,4-dimethylhexene in the product mixture. It relates to a method of manufacturing. The invention also relates to a method for determining the ratio of the amount of 4,4-dimethylhexene formed or the amount of 3-ethyl-2-methylpentene formed to the amount of 3,4-dimethylhexene formed.

Oligomerization is generally understood to mean the reaction of unsaturated hydrocarbons to form correspondingly longer chain hydrocarbons, so-called oligomers. Thus, for example, an olefin (octene) having eight carbon atoms can be formed by oligomerization of two olefins (butene) having four carbon atoms. Oligomerization between two molecules is also referred to as dimerization.

The resulting oligomers are, for example, intermediates used for the preparation of aldehydes, carboxylic acids and alcohols. Oligomerization of olefins is carried out industrially on a large scale, either homogeneously using dissolved catalysts, or heterogeneously on solid catalysts, or using biphasic catalyst systems.

In the case of processes by heterogeneous catalysis, oligomerization on acidic oligomerization catalysts has long been known. Industrially used systems include acidic catalysts on the support, for example zeolites or phosphoric acid. In this case an isomeric mixture of olefins somewhat branched is obtained. In this case the term acidic catalysis or acidic catalyst expresses Bronsted acid, ie the catalyst provides catalytically active protons. In the related art, in the case of oligomerization by non-acidic heterogeneous catalysis of olefins with high dimer selectivity, nickel compounds on support materials are often used, where nickel does not provide protons and does not provide electron pair acceptors ( Lewis acid). WO 95/14647 A1 thus describes a nickel catalyst comprising a support material consisting of component titanium oxide and / or zirconium oxide, silicon oxide and optionally aluminum oxide for olefin oligomerization. On this catalyst, the mixture of linear butenes is oligomerized to C8-olefins with selectivity less than 75%. It is believed that the catalytic activity of the nickel-based heterogeneous catalyst for oligomerization of olefins is based on the interaction between the nickel cation and the surface aluminum atom.

In the case of oligomerization, various mechanisms exist that allow oligomerization to proceed. This includes acid catalysis, in which olefins form carbenium ions with the acid center of the catalyst, where the carbenium ions can react with double bonds of additional olefins to form new C-C bonds. Because carbenium ions are best stabilized at the most highly branched sites of the cation, highly branched oligomers are formed, almost exclusively related to fuel production. For further processing to provide final chemical products such as plasticizers or surfactants, in particular, oligomers having a relatively high linearity are industrially required. An additional mechanism is the coordination mechanism, wherein the first olefin is coordinatively bound to the catalyst. Additional olefins are attached to it, leading to the formation of new C-C bonds, leading to the formation of oligomers. The product of this mechanism is typically less highly branched.

Compared to known oligomerization methods, there is still a need to develop new process-driven approaches that lead to improvements in conversion and / or selectivity when used in oligomerization of olefins that give linear products. It is therefore an object of the present invention to provide an oligomerization method which makes it possible to achieve higher selectivity and higher conversion for higher linear products, which are monitored using specific product isomers through oligomerization. .

It is a further object of the present invention to be able to quantify the saturation of the catalytic acid center with nickel, thereby making it possible to achieve an improved prediction of the suitability of the catalyst for industrially large scale oligomerization. It is a further object of the present invention to be able to interpret the catalyst data to identify the deactivation of specific catalyst centers during the formation of the catalyst and during the reaction. Since oligomerization is performed as a continuous operation at elevated pressures, taking a catalyst sample during the operation is difficult, if not impossible. It is therefore very important to be able to confirm the state of the catalyst using the formed product for the estimation of further run times and for the estimation of the expected product spectrum.

The object underlying the present invention has been achieved using an oligomerization method according to claim 1 and a determination method of saturation according to claim 7. Preferred embodiments are specified in the dependent claims.

The process according to the invention is a process for oligomerization of n-butenes wherein a reactant stream containing n-butenes is passed over a mesoporous nickel-containing aluminosilicate catalyst to form a product mixture, the product mixture Monitor the ratio of the amount of 4,4-dimethylhexene formed to the amount of 3,4-dimethylhexene formed, and the threshold for the ratio (amount of 4,4-dimethylhexene / amount of 3,4-dimethylhexene) Characterized in that the catalyst is replaced when this is exceeded, wherein the threshold for the ratio (amount of 4,4-dimethylhexene / amount of 3,4-dimethylhexene) is 0.05 or less, preferably 0.01 or less, particularly preferred Preferably to 0.005 or less.

Determining the ratio comprises initially determining the amount of the individual isomers and preferably determining the ratio therefrom using gas chromatography. To achieve better separation efficiency, the sample to be analyzed (product mixture) can be hydrogenated with hydrogen as carrier gas on a heterogeneous Pd-containing catalyst before it reaches the separation column. The alkanes obtained therefrom are more readily distinguishable than the C8 olefin isomers formed in oligomerization.

The ratio (amount of 4,4-dimethylhexene / amount of 3,4-dimethylhexene) is used to determine the periodicity of the sample of the product mixture from the process continuously, ie without interruption, or discontinuously, ie during operation. By phosphorus extraction, it can be determined. The ratio (amount of 4,4-dimethylhexene / amount of 3,4-dimethylhexene) is preferably determined discontinuously by taking samples from the product mixture carried out at regular intervals. The spacing between regular samplings is freely selectable and depends on the equipment in operation. In discontinuous determination of ratios the interval between samplings may in principle be an interval of 1 to 59 minutes, 1 to 23 hours, 1 to 6 days or 1 to 20 weeks. The spacing can also vary, ie it can be longer, for example after installation of fresh catalyst and shorter over time.

Surprisingly, monitoring the ratio of 4,4-dimethylhexene to 3,4-dimethylhexene is particularly advantageous when used in the oligomerization process according to the invention, with higher product and higher conversion and / or higher It has been found to make it possible to achieve selectivity. The smaller this ratio is, the lower the rate of acidic catalysis in oligomerization, resulting in less amount of higher branched oligomers formed. However, as the ratio of 4,4-dimethylhexene to 3,4-dimethylhexene increased, formation occurred on the catalyst surface. This makes it possible to determine the average degree of branching that the formed oligomer will have for further work. If a certain threshold is exceeded during the process, the catalyst must be replaced. It is therefore possible to achieve a substantially uniform high linearity of the oligomers formed, because by setting a suitable threshold for the ratio, it is possible to stop the process early and replace the catalyst before a relatively large amount of branched by-products are formed. Because there is.

If catalyst replacement is required due to the exceeding of the threshold, the catalyst used is replaced with fresh catalyst. Depending on the structure of the installation, this proceeds in a manner known to those skilled in the art. The fresh catalyst may be a freshly prepared catalyst or a used but regenerated catalyst.

The reactant stream containing n-butene may also be a stream of pure n-butene but this is hardly feasible industrially. Industrial mixtures containing N-butene and usable as reactant streams include light petroleum fractions from refineries, C ₄ fractions from FC crackers or steam crackers, mixtures from Fischer-Tropsch synthesis, dehydrogenation of butane From mixtures, mixtures formed by metathesis or other industrial processes. Mixtures of n-butenes suitable for the process according to the invention are for example obtainable from the C ₄ fraction of steam crackers. In this case butadiene is removed in the first step. This is done by extraction or extractive distillation of butadiene or selective hydrogenation thereof. In both cases, butadiene-free C ₄ -fractions, ie, raffinate I, are obtained. In the second step, isobutene is removed from the C ₄ -stream, for example by the preparation of methyl tert-butyl ether (MTBE). Another alternative includes the reaction of isobutene with water from raffinate I to give tert-butanol, or oligomerization by acid-catalysis of isobutene to give diisobutene. As desired, the new substantially isobutene-free C ₄ -fraction Raffinate II contains n-butene and possibly butane.

In a preferred embodiment raffinate I (butadiene-free C4 fraction from steam cracker) or raffinate II (butadiene- and isobutene-free C4 fraction from steam cracker) is fed to the process as a reactant stream.

A further alternative to the preparation of suitable olefin mixtures is to apply raffinate I, raffinate II or similarly constructed hydrocarbon mixtures to the hydroisomerization in a reactive column. This may in particular provide a mixture of 2-butene, a small proportion of 1-butene and possibly n-butane and also isobutane and isobutene.

Depending on the origin and aftertreatment of the reactant stream, compounds comprising heteroatoms, in particular nitrogen-, sulfur- and / or oxygen-containing compounds, may be present in the stream.

The oligomerization process according to the invention is preferably carried out at a temperature in the range from 50 ° C to 200 ° C, preferably in the range from 60 ° C to 180 ° C, particularly preferably in the range from 60 ° C to 130 ° C. In the process according to the invention the pressure is preferably in the range from 10 to 70 bar, particularly preferably in the range from 15 to 42 bar.

In a further preferred embodiment, the reactants are in the liquid phase in the process according to the invention. If oligomerization is carried out in the liquid phase, for this the parameter pressure and temperature must be set such that the reactants are present in the liquid phase.

In the oligomerization process according to the invention, the weight-based space velocity (reactant mass per unit catalyst mass and per unit time; weight space-time velocity (WHSV)) is preferably 1 g of reactant per gram of catalyst and per h (= 1) h ⁻¹ ) to 190 h ⁻¹ , preferably 2 h ⁻¹ to 35 h ⁻¹ , particularly preferably 3 h ⁻¹ to 25 h ⁻¹ .

The oligomerization catalyst used according to the invention comprises at least nickel oxide and silicates as support material, preferably amorphous aluminosilicates. In the context of the present invention, "amorphous" should be understood to mean the properties of a solid resulting from the fact that the solid does not have a crystalline structure, ie it does not have a long-range order. However, in the context of the present invention it cannot be excluded that the amorphous silica-alumina support material has a small crystalline domain. The amorphous silica-alumina support material is not a crystalline material, for example not a zeolite material.

Nickel-containing aluminosilicate catalysts used in the process according to the invention are mesoporous, ie comprise at least mesopores. The average pore diameter of the aluminosilicate catalyst used is preferably at least 0.7 nm. The average pore diameter can be determined by mercury porosimetry according to DIN 66133 (version 193-06).

The nickel-containing aluminosilicate catalyst according to the present invention is preferably 0.1 to 51% by weight, preferably 1 to 42% by weight, based on the total composition of the mesoporous nickel-containing aluminosilicate catalyst, Particularly preferably nickel in an amount of from 5% to 33% by weight. In a particularly preferred embodiment of the invention, the oligomerization catalyst is substantially free of titanium dioxide and / or zirconium dioxide, and the oligomerization catalyst is in particular in its total composition, less than 0.5% by weight, preferably less than 0.1% by weight. , Particularly preferably less than 0.01% by weight of titanium dioxide and / or zirconium dioxide.

According to the invention, the nickel-containing aluminosilicate catalyst has a specific surface area of 150 to 700 m² / g, preferably 190 to 600 m² / g, particularly preferably 220 to 550 m² / g (calculated according to BET). May have The BET surface area is measured by nitrogen physisorption according to DIN ISO 9277 (version 2014-01).

In a further preferred embodiment the nickel-containing aluminosilicate catalyst has a silicon-aluminum ratio (Si / Al) of 1 to 100, preferably 2 to 80, particularly preferably 3 to 50.

Suitable reactors that can be used to carry out the process according to the invention include reactors known to those skilled in the art, which allow the oligomerization to be carried out continuously or discontinuously. In a preferred embodiment a fixed bed reactor or slurry reactor operated continuously or discontinuously is used to carry out the oligomerization process according to the invention. The process is carried out in particular under heterogeneous catalysis.

In a preferred embodiment, the degree of dimerization (also referred to as "percent selectivity based on dimerization") for the product / product stream obtained from the oligomerization, based on the converted reactants, is at least 60%, more preferably Is at least 75%, particularly preferably at least 80%.

The linearity of the oligomerization product / dimer formed is represented by the ISO index which indicates the average number value of the methyl branches in the dimer. For example (if the reactant is butene), the ISO index of the C8 fraction is 0 for n-octene, 1 for methylheptene and 2 for dimethylhexene. The lower the ISO index, the more linear the structure of the molecules in each fraction. The ISO index is calculated by the formula:

Thus, dimer mixtures with an ISO index of 1.0 have exactly one methyl branch on average per dimer molecule.

The ISO index of the product from the oligomerization process according to the invention is preferably 0.8 to 1.2, more preferably 0.8 to 1.15.

The oligomers produced by the process according to the invention are used in particular for the preparation of aldehydes, alcohols and carboxylic acids. Thus, for example, dimers of linear butenes provide nonanal mixtures by hydroformylation. This gives the C ₉ alcohol mixture by oxidation or the corresponding carboxylic acid by hydrogenation. C ₉ acid mixtures can be used to prepare lubricants or desiccants. The C ₉ alcohol mixture is a precursor for the preparation of plasticizers, in particular dinonyl phthalate, or DINCH.

The invention also

a) performing oligomerization of n-butene using a mesoporous nickel-containing aluminosilicate catalyst;

b) amounts of C8 isomers formed in oligomerization, in particular n-octene, 3-methylheptene, 3,4-dimethylhexene, 4,4-dimethylhexene, 2,3-dimethylhexene and 3-ethyl-2-methylpentene Quantitatively analyzing the product stream obtained from oligomerization to determine And

c) the amount of 4,4-dimethylhexene formed or the amount of 3-ethyl-2-methylpentene formed to the amount of 3,4-dimethylhexene formed, which is 0.05 or less, preferably 0.01 or less, particularly preferably 0.005 or less Steps to determine the ratio

Also provided is a method for determining the ratio of the amount of 4,4-dimethylhexene formed or the amount of 3-ethyl-2-methylpentene formed to the amount of 3,4-dimethylhexene formed, comprising.

The oligomerization in step a) is preferably carried out at a temperature in the range from 50 ° C to 200 ° C, preferably in the range from 60 ° C to 180 ° C, particularly preferably in the range from 60 ° C to 130 ° C. The pressure in the oligomerization in step a) is preferably in the range from 10 to 70 bar, particularly preferably in the range from 15 to 42 bar.

In a further preferred embodiment the reactants are present in the liquid phase in step a) of the determination process according to the invention and the oligomerization is carried out in the liquid phase. If oligomerization is carried out in the liquid phase, for this the parameter pressure and temperature must be set such that the reactants are present in the liquid phase.

In step a) of the determination process according to the invention, the weight-based space velocity (reactant mass per unit catalyst mass and per unit time; weight space time velocity (WHSV)) is preferably 1 g of reactant per gram of catalyst and per h ( = 1 h ^-1 ) to 190 h ^-1 , preferably 2 h ^-1 to 35 h ^-1 , particularly preferably 3 h ^-1 to 25 h ^-1 .

The oligomerization catalyst according to the invention for the oligomerization in step a) of the determination process comprises at least nickel oxide and an aluminosilicate, preferably amorphous aluminosilicate, as support material. In the context of the present invention, "amorphous" should be understood to mean the properties of a solid resulting from the fact that the solid does not have a crystalline structure, that is, does not have long range regularity. However, in the context of the present invention it cannot be excluded that the amorphous silica-alumina support material has a small crystalline domain. The amorphous silica-alumina support material is not a crystalline material, for example not a zeolite material.

The nickel-containing aluminosilicate used in step a) of the process according to the invention is mesoporous, ie comprises at least mesopores. The average pore diameter of the aluminosilicate catalyst used is preferably at least 0.7 nm. The average pore diameter can be determined by mercury porosimetry according to DIN 66133 (version 193-06).

The nickel-containing aluminosilicate catalyst according to the invention for oligomerization in step a) is preferably from 0.1% to 51% by weight, based on the total composition of the mesoporous nickel-containing aluminosilicate catalyst, It preferably comprises nickel in an amount of 1% to 42% by weight, particularly preferably 5% to 33% by weight. In a particularly preferred embodiment of the invention, the oligomerization catalyst in step a) is substantially free of titanium dioxide and / or zirconium dioxide, and the oligomerization catalyst is, in particular in its total composition, less than 0.5% by weight, preferably Comprises less than 0.1% by weight, particularly preferably less than 0.01% by weight of titanium dioxide and / or zirconium dioxide.

Nickel-containing aluminosilicate catalysts used to determine saturation can in particular be prepared by impregnating aluminosilicates with solutions containing nickel salts or by coprecipitation from a single solution. In both cases, calcination of the nickel-containing aluminosilicate catalyst is subsequently performed at at least 450 ° C. in the presence of an air stream or a nitrogen stream or a mixture of the two.

According to the invention, the nickel-containing aluminosilicate catalyst for oligomerization in step a) is 150 to 700 m 2 / g, preferably 190 to 600 m 2 / g, particularly preferably 220 to 550 m 2 / g. It may have a specific surface area (calculated according to BET). The BET surface area is measured by nitrogen physisorption according to DIN ISO 9277 (version 2014-01).

In a further preferred embodiment the nickel-containing aluminosilicate catalyst used for the oligomerization in step a) has a silicon-aluminum ratio (Si) of 1 to 100, preferably 2 to 80, particularly preferably 3 to 50. / Al).

Suitable reactors that can be used to carry out the determination process according to the invention include those reactors known to those skilled in the art, which allow the oligomerization to be carried out continuously or discontinuously. In a preferred embodiment a fixed bed reactor or slurry reactor operated continuously or discontinuously is used to carry out the determination process according to the invention. The process is carried out in particular under heterogeneous catalysis.

After oligomerization in step a), the obtained product / obtained product stream is characterized for its composition, in particular n-octene, 3-methylheptene, 3,4-dimethylhexene, 4,4-dimethylhexene, 2, Quantitative analysis for 3-dimethylhexene and 3-ethyl-2-methylpentene. This can be accomplished using gas chromatography methods known to those skilled in the art. Further methods known to those skilled in the art, such as IR spectroscopy or other spectroscopy, to characterize the structure of the hydrocarbons eluted can likewise be used to determine the amount of individual isomers.

In step b), before the product / product stream from step a) is sent to gas chromatography, in particular for quantitative analysis, the product / product stream is subjected to a better separation efficiency in the analysis by gas chromatography. It can be applied to hydrogenation. This can be achieved in particular using a palladium-containing catalyst. Hydrogenation can in particular also be carried out using gas chromatography in the form of hydrolytic gas chromatography, in particular using hydrogen as the carrier gas. When the injected sample is hydrogenated, the number of isomers to be determined is drastically reduced. In this case the double bond isomers are no longer distinguished and only the backbone isomers are identified. This information is sufficient to determine the average degree of branching of the product and to determine the ratio of 4,4-dimethylhexene to 3,4-dimethylhexene. The injected sample is separated using a commercially available nonpolar column. The temperature program is optimized to effect effective baseline separation of the octene isomers. Detection is carried out via a flame ionization detector, FID for short. The assignment of the isomers can be carried out through the residence time of each pure material using a mass spectrometer as a detector under the same measurement conditions.

If the change in the oligomerization catalyst is monitored through the method according to the invention, the determination method must be corrected in advance. The catalyst used is the amount of 4,4-dimethylhexene formed or the amount of 3-ethyl-2-methylpentene formed when nickel is absent (= 0 value) and the oligomerization proceeds substantially exclusively by acid catalysis. It should be nickel-free aluminosilicate to determine how high the ratio of the amount of 3,4-dimethylhexene formed to. The correction method carried out before the method according to the invention for determining saturation is particularly

aa) performing oligomerization of n-butene using a mesoporous nickel-free aluminosilicate catalyst at various temperatures and / or loadings (various WHSV);

bb) amounts of C8 isomers formed in oligomerization, in particular n-octene, 3-methylheptene, 3,4-dimethylhexene, 4,4-dimethylhexene, 2,3-dimethylhexene and 3-ethyl-2-methylpentene Quantitatively analyzing the product stream obtained from oligomerization to determine And

cc) determining the ratio of the amount of 4,4-dimethylhexene formed or the amount of 3-ethyl-2-methylpentene formed to the amount of 3,4-dimethylhexene formed

It includes.

Optionally step aa) or step a), ie the oligomerization of the crystallization process according to the invention, comprises oxygen-, sulfur- and / or nitrogen-containing compounds such as, for example, water, carbon monoxide, carbon dioxide, 1-5 Alkylamines with carbon atoms, aldehydes and ketones with 1 to 6 carbon atoms, alcohols with 1 to 6 carbon atoms, carboxylic acids, and ethers and esters with 1 to 8 carbon atoms and 1 to 4 carbon atoms By addition of sulfides, disulfides, thioethers and / or mercaptans with carbon atoms. The amount of addition should not exceed 10 ppmw based on the elements O, S and / or N present in the compound. Based on the trend of the ratios of the 4,4-dimethylhexene and 3,4-dimethylhexene in the product spectrum, this is due to the oxygen species, the sulfur- and / or nitrogen-containing compounds or due to the long operating time It is possible to identify the formation and inactivation processes that occur by the sintering of.

This data makes it possible to make predictions for oligomerization in continuous operation. Depending on the origin of the reactant stream, heteroatom-containing compounds, which may be present in very small amounts in the industrial reactant stream, result in catalytic changes during the reaction, which can be better predicted by the determination process according to the invention.

Example

Catalyst Synthesis:

Granular, amorphous, acidic and meso groups with an average particle diameter of 1-2 mm, an average pore diameter of 11 nm (determined using average pore diameter and mercury porosimetry) and a pore volume of 1 g / l. Silicate aluminosilicate was used as a catalyst. This aluminosilicate (containing no nickel) is used to determine the product distribution of the reaction of n-butene by acid catalysis and to calibrate the determination method according to the invention.

Nickel was introduced by impregnating the aluminosilicate with an aqueous Ni (NO ₃ ) ₂ solution. In the impregnation, a solution of a volume large enough to fill the pore volume was used. Such a method is known to those skilled in the art as initial wet impregnation. The concentration of nickel in the solution was adjusted by initial wet impregnation to provide an aluminosilicate catalyst having a nickel content of 1 wt%, 6 wt% and 14 wt%. This catalyst was then calcined at 550 ° C. for 10 h in the presence of a nitrogen stream.

Product distribution for prepared catalysts:

Oligomerization of n-butene was carried out continuously in a tubular reactor using a loading of 7.5 g olefins per hour and per gram of catalyst (WHSV). The reaction was carried out at 100 ° C. at a pressure of 30 bar. This ensured that the reactants and products were in the liquid phase. The output from the reactor was analyzed using gas chromatography and the ratio of the individual octene isomers in the product spectrum was determined. The ratios of n-octene (n-O), 3,4-dimethylhexene (3,4-DMH) and 4,4-dimethylhexene (4,4-DMH) are summarized in Table 1.

TABLE 1

N-octene (nO), 3,4-dimethylhexene (3,4-DMH) and 4,4-dimethylhexene (4,4-DMH) in the product spectrum and 4,4-DMH to 3,4- Ratio of DMH

The goal of the method is the formation of octene isomers as linear as possible. Catalysts comprising 14% by weight of nickel exhibited the highest amount of n-octene formed and thus also the highest selectivity for linear dimers. As the nickel ratio decreases, n-butene is converted more and more through an acid-catalyzed mechanism, thus increasing the proportion of branched product. This is also reflected in the ratio of 4,4-DMH to 3,4-DMH. The higher the rate of acid catalysis, the greater the ratio. A ratio below 0.05 is characteristic of the onset of coordination catalysis and the highest proportion of n-octene desired is found at a ratio below 0.01.

Claims (14)

A process for oligomerization of n-butenes in which a reactant stream containing n-butenes is passed over a mesoporous nickel-containing aluminosilicate catalyst to form a product mixture, wherein the 4,4-dimethylhexene formed in the product mixture Monitor the ratio of the amount to the amount of 3,4-dimethylhexene formed and replace the catalyst when the threshold for the ratio (amount of 4,4-dimethylhexene / amount of 3,4-dimethylhexene) is exceeded Characterized in that the threshold for the ratio (amount of 4,4-dimethylhexene / 3amount of 3,4-dimethylhexene) is 0.05 or less. The process according to claim 1, wherein the oligomerization process is carried out at a temperature in the range of 50 ° C to 200 ° C, preferably 60 ° C to 130 ° C. The process according to claim 1 or 2, wherein the oligomerization process is carried out at a pressure in the range of 10 bar to 70 bar, preferably 15 bar to 42 bar. The mesoporous nickel-containing aluminosilicate catalyst used in the oligomerization method is 0.1 weight based on the total composition of the mesoporous nickel-containing aluminosilicate catalyst. A nickel calculated as nickel oxide NiO in an amount of% to 51% by weight, preferably 1% to 42% by weight, particularly preferably 5% to 33% by weight. 5. The mesoporous nickel-containing aluminosilicate catalyst used in the oligomerization process is according to any one of claims 1 to 4, wherein Having a Si / Al ratio. The process according to claim 1, wherein the mesoporous nickel-containing aluminosilicate catalyst does not contain titanium dioxide and / or zirconium dioxide. a) performing oligomerization of n-butene with mesoporous nickel-containing aluminosilicate catalyst;
b) amounts of C8 isomers formed in oligomerization, in particular n-octene, 3-methylheptene, 3,4-dimethylhexene, 4,4-dimethylhexene, 2,3-dimethylhexene and 3-ethyl-2-methylpentene Quantitatively analyzing the product stream obtained from oligomerization to determine And
c) determining the ratio of the amount of 4,4-dimethylhexene formed or the amount of 3-ethyl-2-methylpentene formed to the amount of 3,4-dimethylhexene formed that is 0.05 or less;
A method for determining the ratio of the amount of 4,4-dimethylhexene formed or the amount of 3-ethyl-2-methylpentene formed to the amount of 3,4-dimethylhexene formed. 8. The process according to claim 7, wherein the oligomerization in step a) is carried out at a temperature in the range of 50 ° C to 200 ° C, preferably 60 ° C to 130 ° C. The process according to claim 7 or 8, wherein the oligomerization in step a) is carried out at a pressure in the range of 10 bar to 70 bar, preferably 15 bar to 42 bar. 10. The mesoporous nickel-containing aluminosilicate catalyst used in step a) is 0.1 weight based on the total composition of the mesoporous nickel-containing aluminosilicate catalyst. A nickel calculated as nickel oxide NiO in an amount of% to 51% by weight, preferably 1% to 42% by weight, particularly preferably 5% to 33% by weight. The mesoporous nickel-containing aluminosilicate catalyst used in the oligomerization in step a) is 1 to 100, preferably 2 to 80, particularly preferably Having a Si / Al ratio of 3 to 50. The process according to claim 7, wherein the mesoporous nickel-containing aluminosilicate catalyst in step a) does not contain titanium dioxide and / or zirconium dioxide. 13. The oligomerization according to any of claims 7 to 12, wherein the oligomerization is from 1 h ^-1 to 190 h ^-1 , preferably from 2 h ^-1 to 35 h ^-1 , particularly preferably from 3 h ^-1 to 25 the weight spacetime velocity (WHSV) of h ⁻¹ . The method according to any one of claims 7 to 13, wherein the quantitative analysis in step b) is carried out using gas chromatography.